Environment control systems are widely used to maintain ambient conditions within buildings and other structures. These systems include conventional heating and cooling systems as well as more sophisticated systems such as those used to maintain a "clean room" for semiconductor manufacturing processes. Environment control systems generally operate to draw air from within the structure, to process that air and to supply processed air back to the structure. In this manner, environment control systems maintain air conditions within the structure such that the environment is suitable for the structure's purpose.
One problem to which environment control systems have been applied is isolation rooms in health care facilities. It has become increasingly important for health care facilities to have the capability to effectively isolate patients to, for example, prevent the transfer of virulent agents. Possible methods include negative isolation to protect the medical staff and positive isolation to protect a patient. Conventional environment control systems adapted to health care isolation rooms maintain positive or negative pressure differentials in order to maintain the desired isolation. In order to achieve these pressure differentials, conventional systems control the volume of air supplied to the isolation room and to areas outside the isolation room.
A problem with conventional environment control systems is an inability to control particulate levels in a room. Conventional systems merely maintain the pressure differentials and trust that these pressure differentials will achieve a desired concentrations of particulates in a room. However, conventional environment control systems are unable to control particulate levels in a room as an ongoing, real-time process.